Why use Single Number Evaluation Metric in Machine Learning?
If you are tuning hyper-parameters, or attempting various ideas for Learning algorithms, or trying out various options for constructing your learning machine. You will notice your development would be much quicker if you have Single Number Evaluation Metric that quickly lets you tell whether the unknown thing you are doing works better than the last idea, or worse. So when teams start on a project for machine learning, you need to set your problem to a single real number evaluation metric. Let us look at one case.